There are many types of mechanical user interfaces presently available for use with typical computer systems, such as a mouse devices, typewriter-style keyboards, adding machine-style keyboards, track balls, mouse pens, light pens, etc. These devices allow a user to provide meaningful input to a computer via mechanical structures and electrical components. In response to the depression of a button which closes a switch, or to movement, an interface provides electrical signals to a computer. The computer examines the state of the device either periodically or as changes occur. A computer may perform predetermined operations, depending on how it is programmed, in response to input from the interface.
Currently-available position-based devices, such as mouse, track-ball or mouse pen devices, only provide relative position information. That is, there is no predetermined initialization or zero-position of the device. As the device is moved only its movement relative to a prior location can be determined.
Such mechanical user interfaces are typically used to control the position of a cursor on a screen. The initial position of the cursor is predetermined by the computer, so initial position information does not need to be known for the mechanical user interface.
As film editing systems have been increasingly developed for use on typical computer systems, it has been found that available mechanical user interfaces are unnatural to professional film editors. Professional film editors, who typically use analog systems for editing final production films, are familiar with what is known in the art as the Steenbeck controller. The Steenbeck controller is an electromechanical device used for manipulating film for editing, and is typically built into the console of a film editing system in a large production facility. The Steenbeck controller has a handle which is attached to a fixed rotation point. By rotating the handle in one direction, film may be advanced; by moving the handle in the opposite direction, film may be reversed. Film may also be stopped at any fixed point. The Steenbeck controller provides a range of film speeds in both forward and reverse directions: normal speed (sound speed), a range of slow motion, still and fast forward. In response to the actual position of this device, the film is advanced at the desired speed.
The Steenbeck controller is also problematic for film editors because it requires substantial skill to edit film with it. The Steenbeck controller provides fixed zero-, sound speed and fast-forward positions using magnets. A film editor must keep the operating hand on the controller to prevent it from moving, unless it is in one of the fixed positions. Thus, it is difficult to maintain a frame rate which is close to, but not the same as, sound speed, zero-speed or fast-forward. Furthermore, the device only affects the rate of the film advancement. Therefore, it is difficult to provide single-frame advancement; an editor must learn the right "feel" of the device and how to tap it to obtain frame positioning control.
Presently available mechanical user interfaces for computer systems are unnatural because they do not provide actual position information, such as a defined zero-position, and require further means to be useful for computerized film or video editing systems. Moreover, currently available devices for both computer systems and film editing systems do not provide both frame rate control and frame position control (i.e., single frame advancement) of film.
Accordingly, it is an object of the present invention to provide a mechanical user interface for a computer, which feels natural to film editors.
It is another object of the invention to provide a mechanical user interface for a computerized film or video editing system which provides both film rate and film positioning control.